Gas generator

Abstract

A gas generator, particularly for a vehicle occupant restraint system, has at least one igniter ( 12 ), a pyrotechnic solid propellant bed ( 22 ), a combustion chamber ( 20 ) containing the propellant bed ( 22 ) and at least one wall part ( 24 ), the wall part ( 24 ) being arranged in the combustion chamber ( 20 ), which is moved by a gas stream generated on activation of the gas generator into the region of the propellant bed ( 22 ) which is not yet ignited, and in its interior ( 25 ) defines a gas-directing channel reaching into the propellant bed ( 22 ).

1. A gas generator for a vehicle occupant restraint system, with at least one igniter ( 12 ),
 a pyrotechnic solid propellant bed ( 22 ), 
 a combustion chamber ( 20 ) containing said propellant bed ( 22 ) and 
 at least one wall part ( 24 ), 
 said at least one wall part ( 24 ) being constructed so as to be elastic and defining a gas-directing channel in its interior ( 25 ), said channel reaching into said propellant bed ( 22 ), whereas said at least one wall part ( 24 ) extends into a first area of said propellant bed ( 22 ) in a non-activated condition, said first area of said propellant bed ( 22 ) being situated close to said igniter ( 12 ); and 
 wherein the at least one wall part ( 24 ) is constructed so as to expand into a second area of said propellant bed ( 22 ) on activation of said gas generator, said second area of said propellant bed ( 22 ) being situated at the end of said combustion chamber ( 20 ) that is placed remotely from said igniter ( 12 ). 
 
     
     
       2. The gas generator according to  claim 1  wherein said at least one wall part ( 24 ) is hollow, has an interior ( 25 ) and an exterior ( 27 ) and is at least partially open radially during a movement, in order to allow hot gas to flow between the interior ( 25 ) of the at least one wall part ( 24 ) and the exterior ( 27 ) of the at least one wall part ( 24 ). 
     
     
       3. The gas generator according to  claim 1  wherein an additional wall part is constructed so that it moves as a whole in said combustion chamber ( 20 ). 
     
     
       4. The gas generator according to  claim 1  wherein said at least one wall part ( 24 ) is a spring. 
     
     
       5. The gas generator according to  claim 1  wherein said at least one wall part ( 24 ) has an open inflow end ( 31 ). 
     
     
       6. The gas generator according to  claim 5  wherein said at least one wall part ( 24 ) has an open or closed outflow end ( 33 ) opposed to said inflow end ( 31 ), by which said at least one wall part ( 24 ) is moved ahead further into said solid propellant bed ( 22 ). 
     
     
       7. The gas generator according to  claim 1  wherein said at least one wall part ( 24 ) divides the combustion chamber ( 20 ) on movement into a radially inner and a radially outer section. 
     
     
       8. The gas generator according to  claim 1  wherein there is a main direction of flow in said combustion chamber ( 20 ) and said at least one wall part ( 24 ) is moved in this direction. 
     
     
       9. The gas generator according to  claim 1  wherein a mounting is provided for an additional wall part. 
     
     
       10. The gas generator according to  claim 9  wherein said mounting is a linear guide. 
     
     
       11. The gas generator according to  claim 9  wherein said mounting is a fastening of said additional wall part on one side. 
     
     
       12. The gas generator according to  claim 1  wherein an additional wall part is a cylindrical hollow body, with generated gas flowing into an inflow end. 
     
     
       13. The gas generator according to  claim 1  wherein in the non-activated state of said gas generator, propellant of said propellant bed ( 22 ) is situated inside an additional wall part. 
     
     
       14. The gas generator according to  claim 1  wherein a dividing wall ( 18 ) is provided and, in the non-activated state of said gas generator, said at least one wall part ( 24 ) being adjacent to said dividing wall ( 18 ). 
     
     
       15. The gas generator according to  claim 14  wherein said dividing wall ( 18 ) has at least one through-flow opening ( 38 ) which opens into said interior ( 25 ) of said at least one wall part ( 24 ). 
     
     
       16. The gas generator according to  claim 1  wherein said igniter ( 12 ) is adjacent to said dividing wall ( 18 ) and said dividing wall ( 18 ) is adjacent to said hollow interior ( 25 ) of said at least one wall part ( 24 ). 
     
     
       17. The gas generator according to  claim 1  wherein said at least one wall part ( 24 ) is a helical spring. 
     
     
       18. A gas generator, for a vehicle occupant restraint system, with at least one igniter ( 12 ),
 a pyrotechnic solid propellant bed ( 22 ), 
 a combustion chamber ( 20 ) containing said propellant bed ( 22 ) and 
 at least one wall part ( 24 ), 
 said at least one wall part ( 24 ) being constructed so as to be elastic and arranged in said combustion chamber ( 20 ), which is moved by a gas stream generated on activation of said gas generator into a region of said propellant bed ( 22 ) which is not yet ignited, and which defines a gas-directing channel in its interior ( 25 ), said channel reaching into said propellant bed ( 22 ), 
 wherein the elastic at least one wall part ( 24 ) is constructed so as to having an initial length, in a non-activated state of the gas generator, of a maximum of 80% of the length of the propellant bed ( 22 ) and the length of said elastic at least one wall part ( 24 ) extends, in an activated state of the gas generator, beyond said initial length to a maximum length up to a gas-permeable wall ( 44 ) which constitutes an end wall of said combustion chamber ( 20 ) more remote of said igniter ( 12 ).